Sliding panels such as doors or windows have been used in residential and business construction for some time, and a number of systems for securing them against unwanted entry have concurrently developed.
In recent decades, the structural improvement in and the increased availability of larger panels of glass supported by smaller and lighter metal frames, typically extruded aluminum or the like, has resulted in an increased use of door-size panels of glass carried in metal frames which are positioned and supported in surrounding metal frames or jambs in which a generally vertically extending glass panel is arranged for side-to-side horizontal movement in a vertical plane. Certain types of such sliding panels are often referred to as "sliding glass doors".
In one typical arrangement, two such door-size panels are mounted parallel to one another in a frame having a width approximately double that of the individual panels. One of the panels is usually fixed in place immediately adjacent one of the vertical frame members while the other is mounted in a track which runs along the top and bottom horizontal frame members. The movable panel can be slid to a position immediately behind the stationary panel, in which arrangement the other portion of the frame defines an open doorway. When the sliding panel is slid to a generally end-to-end relationship with the stationary panel, the entire system forms a closed door.
Such panel arrangements have become quite popular, particularly in residential construction and are widely found in individual homes, townhouses, condominiums, and apartment units.
Because the usual architectural reason for including such sliding doors in a residential unit is the resulting combination of a large, window-like expanse of glass combined with an easily formed entrance way, such sliding doors usually carry a minimum of excess hardware and generally only include rudimentary locking systems. These are generally not of the character of deadbolt or other more secure types of locks which are commonly in conjunction with hinged or other types of doors formed of wood, metal or composite materials.
Accordingly, such sliding glass panel doors typically provide the most convenient means of unwanted entry into a residential unit which has such doors and therefore represent a security risk as the point of least resistance to unwanted entry to a unit. Various sorts of security hardware have been made available to address this problem. One typical solution is to place a piece of wooden or metal doweling in the track of the sliding glass panel door which is vacant and behind the stationary glass panel door when the sliding door is in the closed position. Although such doweling will initially prevent movement of the sliding door, persons experienced at gaining unwanted entry are generally able to remove such doweling with relative ease by slipping a thin, flat, flexible entry tool between the frame and the doors and thereby dislodging of the dowel.
Another common technique is often used where the frames of the sliding and stationary doors overlap somewhat when the doors are in the closed position. In such cases, a set of aligned holes can be drilled in both frames and a nail or other cylindrical object inserted therein. As with the doweling in the track, such an arrangement will initially prevent unwanted opening of the sliding door. Once again, however, those experienced in gaining unwanted entry know that such nails can be easily dislodged by striking a hard blow to the outermost frame portion at the point where the nail is positioned, typically using a rubber mallet or the like. Because the frame members are held stationary by their structure and surrounding frame, the basic laws of physics dictate that the momentum generated by the delivered blow will be transferred to the removable nail which will literally fly out of the frames upon receipt of such a blow.
More recently, commercial locking mechanisms have appeared for such sliding glass panel doors. These generally take the form of some sort of bar which is mounted horizontally between one vertical edge of the sliding door and one vertical frame member. A number of such designs are available, but most attempt to secure a bar in a horizontal position between the sliding door and its frame in order to secure the door against unwanted entry.
Such commercial devices have failed to gain widespread use or acceptance. First, unless they are well-secured against the door edge and the frame, they can be removed just as easily as can a piece of doweling in the door track. Where secured in somewhat better fashion, such bars can often be dislodged using some sort of leverage tool such as a small crowbar. Other commercially available bars are formed of materials--even metals--which are of insufficient gauge or strength to resist serious entry and will literally bend in place when a sufficient opening force is applied to the sliding door. Typically, the force which can be exerted by a crowbar has proven to be enough to cause such single bars to buckle. It will be understood that, in providing unwanted entry, the sliding door only has to be opened to an extent sufficient for an intruder to pass through, and devices which allow such an extent of movement are essentially useless as security devices, even though they may typically prevent the door from sliding as fully or as freely as it could in their absence.
Finally, where an intruder seeks entry with a particularly serious intent, such horizontally placed individual bars typically cannot prevent the intruder from literally removing the sliding panel from its frame and gaining entry in that manner rather than by forcing the door to slide.
Accordingly, it is an object of the present invention to provide a locking system for securing sliding panels such as sliding glass doors which includes a plurality of locking bars against which an intruder would have to seek entry.
It is another object of the present invention to provide a locking system for sliding panels which maintains the end of the included locking bars securely against the edge of the sliding panel door and the edge of the door frame.
It is a further object of this invention to provide a set of bars and brackets which can form either a triangular or four-point braced barrier against sliding movement of a sliding panel.
It is another object of this invention to provide a locking system for sliding panel doors which makes removal of the door out of its plane of movement much more difficult than has been the case with previous locking systems.
It is a further object of this invention to provide a locking system which permits a sliding glass door to be locked as securely in several partially opened positions as it can be locked in a fully closed position so that ventilation and the like through the partially open door can be accomplished without sacrificing security.
It is another object of the invention to provide locking bars which are pivotally supported in the security system so as to increase the ease of use of such a system.
Finally, it is a further object of this invention to provide a security system which includes locking bars for sliding panel doors which can be optionally unlocked so as to allow full movement of the sliding panel door without removal of the locking system or of the locking bars.